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Pollution peaks on bonfire night

AIR pollution soared in most British cities on Guy Fawkes Night as bonfires filled the air with smoke, according to government statistics. The concentration of tiny smoke particles, known as PM10s and thought to be responsible for 10 000 deaths in Britain each year, exceeded 200 micrograms per cubic metre in Cardiff, Bristol, Liverpool and Leicester and exceeded 300 microrams per cubic metre in Leeds and Birmingham (see Diagram).

The figures, collected by the National Environmental Technology Centre at Culham, were typically four times higher than the night of 4 November and ten times the year-round average. The exception was London, where smoke levels rose only by 50 per cent, probably because rain doused the fires and washed the pollution out of the air.

“This is the first year we have picked up raised concentrations [of PM10] on Guy Fawke’s night,” says Paul Willis of Netcen, “probably because the air was very still across the country, so the smoke did not disperse.”

The term PM10 refers to all particles in the air less than 10 micrometres in diameter. They can penetrate deep into lungs. Average PM10 levels in British cities are around 25 micrograms per cubic metre.

Earlier this year, researchers in Britain were told of American findings which suggest that every increase of 10 micrograms of PM10 in a cubic metre of city air raises death rates from respiratory diseases such as bronchitis and asthma by more than 3 per cent, and raises deaths from heart disease by more than 1 per cent (This Week, 1 October).